[Round 1A 2017] Problem A. Alphabet Cake : https://code.google.com/codejam/contest/5304486/dashboard#s=p0

Alphabet Cake.cpp

//
//  Created by fpdjsns
//  Copyright © 2019 fpdjsns. All rights reserved.
//

/*
 * 시간복잡도 : O(RC)
 * 공간복잡도 : O(RC)
 */

#include<iostream>
#include<vector>
#include<algorithm>
#include<queue>

using namespace std;

int R, C;

// row
vector<vector<char>> setRow(vector<vector<char>> arr) {
	
	for (int i = 0; i < R; i++) {
		queue<int> q;
		char c = '?';
		for (int j = 0; j < C; j++) {
			if (arr[i][j] != '?') {
				c = arr[i][j];
			}
			if (c == '?') {
				q.push(j);
				continue;
			}
			arr[i][j] = c;
			while (!q.empty()) {
				arr[i][q.front()] = c;
				q.pop();
			}
		}
	}
	return arr;
}

// column
vector<vector<char>> setColumn(vector<vector<char>> arr) {
	
	for (int j = 0; j < C; j++) {
		queue<int> q;
		char c = '?';
		for (int i = 0; i < R; i++) {
			if (arr[i][j] != '?') {
				c = arr[i][j];
			}
			if (c == '?') {
				q.push(i);
				continue;
			}
			arr[i][j] = c;
			while (!q.empty()) {
				arr[q.front()][j] = c;
				q.pop();
			}
		}
	}
	return arr;
}

int main() {
	int t;
	cin >> t;

	for (int c = 1; c <= t; c++) {
		cin >> R >> C;
		vector<vector<char>> arr(R, vector<char>(C));
		
		for (int i = 0; i < R; i++) {
			for (int j = 0; j < C; j++) {
				cin >> arr[i][j];
			}
		}

		arr = setRow(arr);
		arr = setColumn(arr);

		printf("Case #%d:\n", c);
		for (int i = 0; i < R; i++) {
			for (int j = 0; j < C; j++) {
				printf("%c", arr[i][j]);
			}
			printf("\n");
		}
	}
	return 0;
}